1. Field of the Invention
The invention generally relates to a projection controlling method and a microelectromechanical systems (MEMS) projection apparatus, and more particularly, to a projection controlling method and a MEMS projection apparatus using a MEMS scanning mirror.
2. Description of Related Art
Microelectromechanical systems (MEMS) generally refers to a technology for developing and manufacturing electronic devices and mechanical structures by using microelectronic technologies and mechanical engineering technologies and miniaturizing related products. Nowadays, laser projection apparatus using MEMS scanning mirror is broadly adopted in smart phones and notebook computers and has gradually become one of the most indispensable components of portable audio/video apparatuses thanks to its small volume and low power consumption.
Generally, a laser projection apparatus projects an image light and forms an image on a screen through its MEMS scanning mirror. While operating a MEMS scanning mirror, the MEMS scanning mirror is respectively controlled by different control signals with corresponding swing frequencies in different scanning directions of the image light on the screen. For example, if the scanning frequency of the image light in the vertical direction of the screen is 60 Hz, the swing frequency of the MEMS scanning mirror in the corresponding direction (for example, the vertical direction) should also be 60 Hz. Thus, the control signal should be a periodic wave signal of 60 Hz in order to achieve the desired image quality.
However, a MEMS scanning mirror has its own resonance frequency. Thus, when a periodic wave signal is input for controlling the MEMS scanning mirror, the MEMS scanning mirror produces a corresponding response to a harmonic component having the resonance frequency in the periodic wave signal, so that bright lines will be produced in the projection image when the image light scans due to the uneven swing speed of the MEMS scanning mirror. Thereby, how to resolve the problem of bright lines and achieve an optimal projection quality is one of the major subjects in the industry.